Re: [orca-list] How to tell if Orca is running?

[Mike Gorse <mgorse alum wpi edu>]

Hi Carolyn,

AT-SPI keeps track of ATs listening for events, to avoid sending out 
events that aren't needed, but it doesn't currently provide a particularly 
convenient API to expose that information to applications or a way for an 
application to tell what kind of AT is running. I should probably add 
something to do this for 2.10; there is an open bug for it, as Joanie 
pointed out. However, it is possible to query the registry daemon to 
determine whether anything is listening for events, by doing the 
programmatic equivalent of this:

dbus-send --type=method_call --print-reply --dest=org.a11y.atspi.Registry /org/a11y/atspi/registry 
org.a11y.atspi.Registry.GetRegisteredEvents

This method call needs to be made on the accessibility bus (which is 
distinct from the session bus), so you first need to fetch the address for 
the accessibility bus. If you are going to use libdbus, then you can call 
atspi_get_a11y_bus() in libatspi to get a DBusConnection to it. If you 
want to use gdbus or some other D-Bus binding, then I'd suggest looking at 
the code for atspi_get_a11y_bus(), since you'll need to replicate it, 
although it should suffice to just fetch the address via the bus launcher 
(ie, to port get_accessibility_bus_address_dbus).

If GetRegisteredEvents isn't implemented (ie, for older versions of 
AT-SPI2), then you'd need to assume that something might be listening.

There are also signals (EventListenerRegistered and 
EventListenerDeregistered) that the registry daemon sends out when event 
listeners are added or removed.

Hth,
-Mike

On Mon, 22 Apr 2013, Carolyn MacLeod wrote:

> Thanks, Julien.
> I'm sure that would work (assuming that I am always looking for the string "orca") but it seems a bit 
> heavyweight to list all processes whenever anyone types an arrow key in a
> table.
> I was hoping that there would be a system flag somewhere.
>
> Joanie? Do you set/clear a flag somewhere to say "there's an AT running"? Sort of like the Mac and Windows 
> examples I sent?
>
> Thanks,
> Carolyn
>
>
> From:
> Julien Claassen <julien mail upb de>
> To:
> Carolyn MacLeod/Ottawa/IBM IBMCA,
> Cc:
> orca-list gnome org
> Date:
> 04/19/2013 04:50 PM
> Subject:
> Re: [orca-list] How to tell if Orca is running?
>
> ________________________________________________________________________________________________________________________________________________________________________________
>
>
>
> Hello Carolyn!
>   I've never done that in code myself, but you could do it the easy way,
> executing "ps -ax". ps relies onthe /proc filesystem, which is present on all
> Linux systems. There are some functions to use the information presented
> through /proc. I believe it's part of glibc.
>   I hope this helps.
>   Warm regards
>         Julien
>
> ----------------------------------------
> http://juliencoder.de/nama/music.html